SUPEREXCHANGE INTERACTIONS IN CU0.5FE0.5RHCRS4

Cu0.5Fe0.5RhCrS4 has been studied by Mossbauer spectroscopy, X-ray dif fraction, and magnetization measurement. The crystal is found to have a cubic spinel structure with a lattice constant a(o) = 9.859 +/- 0.00 5 Angstrom. The iron ions are in ferric states and occupy the tetrahed ral sites. The temperature dependence of both the magnetic hyperfine f ield and magnetization is analyzed by the Neel theory of ferrimagnetis m, which yields the values of three exchange integrals: J(Fe-Cr)/k(B) = -13.07 K, J(Fe-Fe)/k(B) = -6.49 K, and J(Cr-Cr)/k(B) = 8.10 K. The N eel temperature and the Debye temperature are found to be 210 +/- 2 K and 305 +/- 5 K, respectively.